This invention relates to fluid delivery pumping systems, and particularly to systems which are used to provide enteral or parenteral nutrition fluids to a patient.
Several pumping systems are currently in use for delivery of parenteral (intravenous) fluids to the blood vessels of a patient, delivery of enteral nutrition fluids to the stomach or intestine of a patient or delivery of blood or plasma to a patient.
Pumping systems have the advantage of delivering a measured and more accurate dose of fluids to a patient by controlling the fluid flow through the positive action of a fluid pump. Such fluid delivery systems usually involve a motor set, which provides the pumping power, and a disposable delivery set, which includes the plastic tubing which is attached to the motor set and through which either enteral or parenteral fluid is pumped into the patient. Traditionally, such sets are arranged so that the fluid is entirely contained within the set during the pumping action. Commonly used pumping actions include peristaltic pumps and diaphragm pumps wherein the pumping chamber is included as part of the disposable delivery set.
U.S. Pat. No. 3,739,943 discloses an infusion pumping system which uses a delivery set having a disposable piston type syringe and disposable valve. In the system described in this patent, intravenous fluid is directly pumped by the disposable syringe acting in connection with the valve. The volume of fluid delivered by each stroke of the syringe piston is controlled by use of magnetic limit switches. This prior art system provides effective pumping of fluid, but requires the use of a valve arrangement in a disposable pump set which renders the set relatively complex and expensive to manufacture. Further, the delivery set and syringe pump must be primed to be devoid of air prior to use and includes no inherent mechanism for detecting fluid delivery problems.
It is an object of the present invention to provide a fluid delivery set which provides accurate fluid delivery rates, when operated in connection with a pump mechanism, and which also provide a low-cost disposable pump set.
It is a further object of the invention to provide a fluid delivery system which provides detection of fluid delivery problems.
It is a further object of the invention to provide a pump unit for operation with a disposable delivery set and to provide the combination of a pump unit and a disposable set into a fluid delivery system. The present invention additionally involves a new and improved method for pumping fluids from a fluid supply to a fluid outlet in carefully controlled incremental fluid volumes.